This application claims the priority benefit of Taiwan application serial no. 89128259, filed Dec. 29, 2000.
1. Field of Invention
The present invention relates to a gas distribution plate design. More particularly, the present invention relates to a flexible nozzle system for the gas distribution plate of a plasma reaction chamber.
2. Description of Related Art
Plasma is often employed in the fabrication of semiconductor devices and circuits. For example, in thin film deposition, plasma is used for sputtering and plasma-enhanced chemical vapor deposition (PECVD). Plasma is also one of the principle techniques in dry etching operations. In ion implantation, the ion source of an implanting machine is actually plasma produced by conventional plasma production methods. In addition, the ozone used in a tetra-ethyl-ortho-silicate/ozone (TEOS/O3) chemical vapor deposition is also produced from oxygen by a plasma method.
Plasma etching is an anisotropic etching process in which particles are accelerated to a high energy level before being bombarded upon a silicon wafer. FIG. 1 is a schematic cross-sectional view of a conventional plasma reaction chamber. As shown in FIG. 1, gases 100 flow into a reaction chamber 106 via nozzle holes 104 on a gas distribution plate 102 near the top of the chamber. By applying a voltage to the low-pressure gases 100 inside the reaction chamber 106, neutral gaseous molecules are activated and hence forced to dissociate into ions, radicals, molecular fragments and electrons. These particles are accelerated by electric field to high energy before bombarding against a silicon wafer 108 target.
FIG. 2 is a schematic cross-sectional diagram of a portion of the gas distribution plate shown in FIG. 1. As shown in FIG. 2, the gas distribution plate 200 and the nozzle holes 202 in the plate form an integrated unit. The gas distribution plate 200 is made from aluminum, for example and the nozzle holes 202 are formed by drilling. Furthermore, a layer of anodized film 204 (for example, an aluminum oxide Al2O3) is formed over the plate 200 by cathode plating. In general, complicated steps are required to fabricate a gas distribution plate having an appropriate nozzle profile for producing a fluid field suitable for a particular application. In addition, particles and high molecular weight polymers can easily accumulate around and between nozzle holes 202. These accumulated particles are difficult to remove in wet cleaning. Furthermore, since the anodized film 206 inside the nozzle holes 202 is frequently bombarded by high-energy plasma during operation, punch-through of the anodized film 206 may occur. As soon as the anodized film 206 is broken somewhere, the gas distribution plate 200 is no longer usable and needs to be replaced. Hence, the gas distribution plate 200 often has a short life expectancy.
Accordingly, one object of the present invention is to provide a flexible nozzle system in the gas distribution plate of a plasma reaction chamber. Utilizing plasticity and plasma-resisting properties of engineering plastic, the nozzles are fabricated using engineering plastic and employ a modular, flexible and removable design.
A second object of this invention is to provide a flexible nozzle system for the gas distribution plate of a plasma reaction chamber. Through shaping the internal profile of the removable nozzles, a desired gas flow pattern inside the reaction chamber is obtained.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a flexible nozzle system for the gas distribution plate of a plasma reaction chamber. The flexible nozzle system on the gas distribution plate includes a metal plate having a plurality of nozzle engagement holes formed by drilling such that a plurality of removable nozzle modules can easily be gripped by the engagement holes.
This invention also provides a type of removable nozzle module having a cap section with screw slot thereon for rotation and an engaging section linked to the cap section. Each removable nozzle module has a nozzle hole in the middle linking up the engaging section and the cap section.
In brief, this invention provides a nozzle system made from engineering plastic for the gas distribution plate of a plasma reaction chamber. Since nozzles made from engineering plastic can be easily shaped and are resistant to plasma corrosion, the nozzle can be easily cleaned. Moreover, each plastic nozzle can be mounted or dismounted separately. Hence, operating cost can be reduced. Furthermore, the nozzle hole can be shaped into a variety of different profiles because engineering plastic is a workable material. In addition, different gaseous flow patterns can be produced by inserting different types of nozzle modules on the gas distribution plate. Ultimately, a uniform gaseous flow can be produced inside the plasma reaction chamber and a higher wafer yield can be obtained.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.